Rydberg states about dipolar cores: The quantum dynamics of the long-range anisotropic interaction

High Rydberg states about a dipolar molecular core can exhibit special features due to the exceptionally long range of the electrical anisotropy of the core. Unlike all other, more localized, couplings of the Rydberg electron to the ion, here the interaction is not shielded by the centrifugal barrier. The influence of the core even on states of the electron with higher angular momentum l and the significant matrix elements between states that differ considerably in the principal quantum number n make this problem worthy of separate considerations. Using specialized computational techniques (both analytical and numerical) for the exact evaluation of the relevant matrix elements, the role of both inter- and intra-Rydberg series coupling is discussed. The importance of the latter (i.e., the coupling of the Rydberg electron to the rotation of the core) is emphasized. Special attention is given to the role of an external dc electrical field that is different in the present problem in that it does not significantly dilute the strength of the electron-core interaction. A positively charged core can have a dipole moment (defined with respect to its center of mass) larger than that of neutral polar molecules, particularly if the charge is localized. Hence the interseries and intraseries dynamics discussed in this paper can give rise to experimentally measurable special effects.